As part of occupant protection in a collision of a vehicle, a device configured to protect the knees of an occupant by absorbing impact energy acting on the knees is disclosed in Japanese Patent Laid-Open Publication Nos. HEI-9-66788 and HEI-5-238338, for example.
The occupant knee protection device disclosed in the HEI-9-66788 publication will be described with reference to FIG. 8 hereof.
A knee protection device 100 shown in FIG. 8 includes a knee protecting member 102 in a U shape in a side view, extending from a fixed bar 101 which extends transversely at the front of a vehicle body, toward a knee of an occupant seated (not shown). The knee protecting member 102 is a sheet-steel part with a proximal end portion 103 thereof attached to the fixed bar 101, and a distal end portion 104 forming a free end. The distal end portion 104 is opposite to the knee of the occupant with a lower instrument panel 105 there-between.
When impact energy acts on the front of the vehicle, the knee moves in the direction of arrow Xl, striking the distal end portion 104 through the lower instrument panel 105. The U-shaped knee protecting member 102 deforms forward, absorbing impact energy acting on the knee, and thereby protecting the knee.
Next, the occupant knee protection device disclosed in the HEI-5-238338 publication will be described with reference to FIGS. 9A and 9B hereof FIG. 9A illustrates a state before a collision, and FIG. 9B illustrates a state after a collision.
A knee protection device 200 shown in FIG. 9A includes an elongated knee protecting member 202 extending rearward and downward from a fixed bar 201 which extends transversely at the front of a vehicle body, toward a knee of an occupant seated (not shown). A proximal end portion 203 of the knee protecting member 202 is attached to the bar 201, and a distal end portion 204 is fastened to a knee panel 205 with a bolt and nut. The distal end portion 204 is opposite to the occupant's knee with the knee panel 205 therebetween. The knee protecting member 202 is a hollow cross-section frame. The inside of the frame is divided by a plurality of ribs 206 and thus integrally formed with a plurality of inner frames 207 in a longitudinal direction.
When impact energy acts on the front of the vehicle, the knee moves in the direction of arrow X2, striking the distal end portion 204 through the knee panel 205. As a result, as shown in FIG. 9B, the knee protecting member 202 plastically deforms at its distal end side, absorbing impact energy acting on the knee, and thereby protecting the knee.
The knee protecting member 102 shown in FIG. 8 is disposed in front of the occupant's knee within a passenger compartment, and thus requires consideration to be given to its arrangement relative to interior parts around it such as an instrument panel and electrical components installed in the panel. Since the arrangement and shape of the interior parts are determined based on the perspective of overall vehicle design, it is preferred that design freedom be as great as possible.
It is required for the knee protecting member 102 to be provided with sufficient capability to absorb impact energy. The height of the occupant's knee varies greatly between individuals. Thus, the action point of impact energy on the distal end portion 104 of the knee protecting member 102 also varies up and down. Even when the action point varies as described above, it is required for the knee protecting member 102 to have sufficient capability to absorb impact energy. For this, it is conceivable to increase the size of the knee protecting member 102 in consideration of variation of the action point of impact energy. However, under the constraint that design freedom in the passenger compartment such as freedom in the arrangement and shape of interior parts should be ensured, there is a limit to the size of the knee protecting member 102, and more consideration is required.
The same is true for the knee protecting member 202 shown in FIGS. 9A and 9B.
For these reasons, there is a desire for an assembly that allows sufficient and stable energy absorbing performance to be provided irrespective of vertical variation of the action point of impact energy on a knee protecting member, and also allows reduction in size of the knee protecting member.